[codex] Add issue monitor liveness controls (#4988)

## Thinking Path

> - Paperclip is a control plane for autonomous AI companies where work
must stay observable, governable, and recoverable.
> - The task/heartbeat subsystem owns agent execution continuity, issue
state transitions, and visible recovery behavior.
> - Waiting on an external service is not the same as being blocked when
the assignee still owns a future check.
> - The gap was that agents had no first-class one-shot monitor state
for external-service waits, so recovery could look stalled or require ad
hoc comments.
> - This pull request adds bounded issue monitors that can wake the
owner, clear exhausted waits, and produce explicit recovery behavior.
> - It also surfaces monitor status in the board UI and documents when
to use monitors versus `blocked`.
> - The benefit is clearer liveness semantics for asynchronous waits
without weakening single-assignee task ownership.

## What Changed

- Added issue monitor fields, shared types, validators, constants, and
an idempotent `0075` migration for scheduled monitor state.
- Added server-side monitor scheduling, dispatch, recovery bounds,
activity logging, and external-ref redaction.
- Added board/agent route coverage for monitor permissions and child
monitor scheduling.
- Added issue detail/property UI for monitor state, a monitor activity
card, and Storybook stories for review surfaces.
- Documented monitor semantics and recovery policy behavior in
`doc/execution-semantics.md`.
- Addressed Greptile review feedback by preserving monitor state in
skipped-stage builders and making board monitor saves send `scheduledBy:
"board"`.

## Verification

- `pnpm install --frozen-lockfile`
- `pnpm run preflight:workspace-links && pnpm exec vitest run
server/src/__tests__/issue-execution-policy-routes.test.ts
server/src/__tests__/issue-execution-policy.test.ts
server/src/__tests__/issue-monitor-scheduler.test.ts
server/src/__tests__/recovery-classifiers.test.ts
ui/src/components/IssueMonitorActivityCard.test.tsx
ui/src/components/IssueProperties.test.tsx
ui/src/lib/activity-format.test.ts`
- First run passed 5 files and failed to collect 2 server suites because
the worktree was missing the optional `acpx/runtime` dependency.
- After `pnpm install --frozen-lockfile`, reran the 2 failed suites
successfully.
- `pnpm exec vitest run
server/src/__tests__/issue-monitor-scheduler.test.ts
server/src/__tests__/recovery-classifiers.test.ts`
- `pnpm --filter @paperclipai/shared typecheck && pnpm --filter
@paperclipai/db typecheck && pnpm --filter @paperclipai/server typecheck
&& pnpm --filter @paperclipai/ui typecheck`
- `pnpm exec vitest run
server/src/__tests__/issue-execution-policy.test.ts
ui/src/components/IssueProperties.test.tsx`
- `pnpm --filter @paperclipai/server typecheck && pnpm --filter
@paperclipai/ui typecheck`
- `pnpm exec vitest run
ui/src/components/IssueMonitorActivityCard.test.tsx
ui/src/components/IssueProperties.test.tsx`
- `pnpm --filter @paperclipai/ui typecheck`
- Storybook screenshot captured from
`http://127.0.0.1:6006/iframe.html?viewMode=story&id=product-issue-monitor-surfaces--monitor-surfaces`
with Playwright.

## Screenshots

![Issue monitor Storybook
surfaces](https://raw.githubusercontent.com/paperclipai/paperclip/PAP-2945-when-a-task-is-waiting-for-an-_external-service_-what-state-should-it-be-in-and-what-recovery-method-could-it-h/docs/pr-screenshots/pap-2945/monitor-surfaces.png)

## Risks

- Medium: this changes heartbeat recovery behavior for scheduled
external-service waits, so regressions could affect wake timing or
recovery issue creation.
- Migration risk is reduced by using `IF NOT EXISTS` for the new issue
monitor columns and index.
- External monitor references are treated as secret-adjacent and are
intentionally omitted from visible activity/wake payloads.

> For core feature work, check [`ROADMAP.md`](ROADMAP.md) first and
discuss it in `#dev` before opening the PR. Feature PRs that overlap
with planned core work may need to be redirected — check the roadmap
first. See `CONTRIBUTING.md`.

## Model Used

- OpenAI Codex, GPT-5 coding agent with repository tool use and terminal
execution.

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [x] If this change affects the UI, I have included before/after
screenshots or Storybook review surfaces
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [x] I will address all Greptile and reviewer comments before
requesting merge

---------

Co-authored-by: Paperclip <noreply@paperclip.ing>

ui/src/components/IssueMonitorActivityCard.tsx

@@ -0,0 +1,71 @@
+import type { Issue } from "@paperclipai/shared";
+import { Button } from "@/components/ui/button";
+import { formatMonitorOffset } from "@/lib/issue-monitor";
+import { formatDateTime } from "@/lib/utils";
+
+function resolveScheduledMonitor(issue: Issue) {
+  const nextCheckAt =
+    issue.monitorNextCheckAt?.toISOString() ??
+    issue.executionPolicy?.monitor?.nextCheckAt ??
+    issue.executionState?.monitor?.nextCheckAt ??
+    null;
+  if (!nextCheckAt) return null;
+
+  return {
+    nextCheckAt,
+    notes: issue.executionPolicy?.monitor?.notes ?? issue.monitorNotes ?? issue.executionState?.monitor?.notes ?? null,
+    attemptCount: issue.monitorAttemptCount ?? issue.executionState?.monitor?.attemptCount ?? 0,
+    serviceName: issue.executionPolicy?.monitor?.serviceName ?? issue.executionState?.monitor?.serviceName ?? null,
+  };
+}
+
+interface IssueMonitorActivityCardProps {
+  issue: Issue;
+  onCheckNow?: (() => void) | null;
+  checkingNow?: boolean;
+}
+
+export function IssueMonitorActivityCard({
+  issue,
+  onCheckNow = null,
+  checkingNow = false,
+}: IssueMonitorActivityCardProps) {
+  const monitor = resolveScheduledMonitor(issue);
+  if (!monitor) return null;
+
+  return (
+    <div className="mb-3 rounded-lg border border-border bg-muted/30 px-3 py-2">
+      <div className="flex flex-col gap-2 sm:flex-row sm:items-center sm:justify-between">
+        <div className="min-w-0">
+          <div className="text-sm font-medium text-foreground">Monitor scheduled</div>
+          <div className="text-xs text-muted-foreground">
+            Next check {formatDateTime(monitor.nextCheckAt)} ({formatMonitorOffset(monitor.nextCheckAt)})
+          </div>
+          {monitor.notes ? (
+            <div className="mt-1 text-xs text-muted-foreground">{monitor.notes}</div>
+          ) : null}
+          {monitor.serviceName ? (
+            <div className="mt-1 text-xs text-muted-foreground">
+              {monitor.serviceName}
+            </div>
+          ) : null}
+          {monitor.attemptCount > 0 ? (
+            <div className="mt-1 text-xs text-muted-foreground">Attempt {monitor.attemptCount}</div>
+          ) : null}
+        </div>
+        {onCheckNow ? (
+          <Button
+            type="button"
+            variant="outline"
+            size="sm"
+            className="shrink-0 shadow-none"
+            onClick={onCheckNow}
+            disabled={checkingNow}
+          >
+            {checkingNow ? "Checking..." : "Check now"}
+          </Button>
+        ) : null}
+      </div>
+    </div>
+  );
+}